Filter frame



FILTER FRAlVIE Verner E. Sprouse and Lowell E. Sprouse, both of 1804 E. 22nd St., Columbus, Ind.

Filed Oct. 15, 1958, Ser. No. 767,374

1 Claim} (Cl- 183-51) This invention relates to a frame particularly adapted for use in forming filters for air and gases, such for example as may be used'in heating and air conditioning units where dust and dirt is to be filtered from flowing currents of heated or cooled air through ducts.

A primary purpose of the invention is to provide a simplified structure which may be readily produced through a minimum of operations in manufacture, and may be quickly and cheaply assembled to form a rather rigid frame to hold the filtering medium, whereby the frame will remain intact during removing and cleaning operations of the filtering frame apart from and return to its normal holding means.

The frame is intended to hold. a foraminous or porous filtering medium which may be made out of a number of different materials, such as knitted or woven metal threads formed in sheets which may be overlapped to give the desired thickness of the filtering medium. Such medium needs to be held around its marginal edges to prevent displacement from the frame and also to prevent undue travel such as by sagging or bowing of the material between the frame sides. ginal portions of the filtering medium must be held against movement in the frame, and remain so held during cleaning operations.

The frame is so designed that it may be made in any number of polygonal shapes either formed by one element embodying as a unit a number of segments integrally joined, or two or more individual segments one bent from the other, or individual segments requiring interlocking end connections one with the other. By segment is meant a length without an angular bend intermediate its ends.

,. v The frame is made preferably out of metal and in segments, such for example having an L shape for the rectangular form of frame. One of these L shapes is indicated in Fig. 2, and in Fig. 1 in assembled relation.

Referring further to the drawings, Fig. l is a View in top plan and partial section of a complete frame embodying the invention;

Fig. 2 is a view in top plan on an enlarged scale of an element having two segments in L shape;

Fig. 3 is a view in further enlarged scale .in partial section, and in disassembled relation of an interconnecting corner construction for interengagement of two segments;

between legs of the segments as illustrated in Fig. 2;

In other words, the mar- Fig. 8 is a view in top plan and partial section of a V modified form of the frame;

ice

Fig. 9 is a view in top plan and partial section of a further modified form of the invention; and

Fig. 10 is a View in top plan and partial section of a still further modified form of the invention.

The element generally designated by numeral 10 illustratedin Fig. 2 has a base 11 from which is turned at ninety degrees an enclosing leg 12, and in turn from the upper edge of which is turned inwardly over the base 11 a presser leg 13. Intermediate ends 14 and 15, the base 11 and the presser leg 13 are mitered so that the element may be bent upon itself at right angles into two segments 18 and 18a for the rectangular shape of frame, forming the integral corner or bend. 16. To permit this bending, Figs. 1 and 7, the lower base 11 is mitered to abut along theline 17 at forty five degrees to the enclosing leg 12, thus dividing the member 10 into the two segments 18 and 18a. Thepresser legs are initially mitered at the bend 16 to approximately fiftyfive degreesso that the leg '13 in eachsegment 18 and 18a may be bent angularly vdownwardly toward the base 11 as indicated in Fig. 6, and meet one another along the line 19, Fig. 2.

The end portions 14 and 15 of the. member 10 are brought up to ends 15 and 14 respectively of .a second member 10 herein designated as 19A. .The member 10A is an exact duplicate ofthemember 10. At the end 14 of the member 10A, Figs. 1 and 3, the enclosing leg 12 is offset inward-1y between the base :11 and the presser leg 13 by a short length 20 and thence preferably turned inwardly at an angle such as approximately five degrees to terminate in the tongue 21 which lies between the base'11 and the overhanging'presser leg 13. 'In the offset portion 20, there is provided avertically extending slot 22. V i

This slot 22 receives therethrough an inserted foot 23 formed as follows. The foot 23 is turned from the end 15 of the enclosing leg 12, Figs. 3 and .5, atright angles thereto, and is provided with an end portion 24 turned substantially at fifteen degrees from the .plane of the foot 23 as it extends from the end 15. The opposing edges of the ba at he n 14 m 15 F are mitered at forty-five degrees so as to come into abutment along the line 17 when they are brought one against the other. When the two end portions =14 and 15 are in that abutment, the foot 23 will have been. inserted through the slot 22 tohave the end portion 251 on the inside of the leg 12, this inclined portion being provided to facilitate entry of the foot 23 through the slot 22, a portion of the foot 23 lying firmly against the inside of the leg 12 as indicated in Fig. 5. The foot 23 is further provided with apair of vertically spaced apart abutments or fingers 25 and 26 hereinshown as being punched inwardly from the foot 23, and so located and proportioned that they may be forced through the slot 22 and come back against the edge of the slot 22 as best indicated in Fig. 5, so as to prevent withdrawal of the foot 23. It is to be particularly noted that these fingers 25 and 26 are vertically spaced apart, that is one toward an adjacent upper and lower margin respectively of the foot 23. This spacing apart serves to present not only abutments to prevent withdrawal. of the foot 23, but also to give spaced apart abutting contacts with the margin of the slot 22 thereby, in conjunction, with the abutment of the base 11 mitered edges to prevent a twisting action of the frame at the corner, that is,1 tw-ist ing from a generally planar interconnection of the two members 10 and 10A. I v ;fi This same interconnection of the ends 14 and 15 is had at the diagonally opposite abutting ends of the members 1t and 10A, Fig. 1. As further security means against displacement of one member '10 from its abutting member 10A, it is preferred that a staple 27 be passed through the opposing ends of the base 11 along the line 17, a staple 27 straddling that line, and clinched over by ends 27a and 27b on the inside, that is the topside of the base 11. The terms top and bottom sides herein employed refer merely to the presentation of the frame in the drawing, and not necessarily top and bottom sides of the frame'when positioned in use.

The frame thus assembled will normally have the upper presser legs 13 disposed at ninety degrees from the enclosing leg 12 as indicated by the dash line position in Fig. 6, so as to facilitate the entrance thereunder and over the base 11 of a filtering medium generally designated by the numeral 28, Fig. 6. The presser leg in its original formation is provided with a plurality of barbs herein shown generally triangular in shape, designated by the numeral 29, which are punched from the leg 13 near its free edge, the apices being directed toward the enclosing leg 12. These barbs 29 are turned from the plane of the presser leg 13 in each instance substantially ninety degrees. While it has not heretofore been expressly stated, the base 11, enclosing leg 12, and presser leg 13 extend entirely around the frame without interruption except at the corners as above described.

The filtering medium 28 is as above mentioned normally built up of a plurality of separate sheets of knitted or woven material, in a loose arrangement so that the overall medium is compressible.

With the medium 28 in position, Fig. 6, the presser legs 13 are bent downwardly from the upper marginal portion of the enclosing leg 12 through a radius 30 to bring the free edge 31 of the presser leg in each instance downwardly against the filtering medium 28 thereby compressing that marginal edge portion against the base 11. Simultaneously with that travel of the presser leg 13 down against the filtering medium 28, the barbs 29 will have initially engaged in the marginal portion of the medium 28 and continued downward travel of the presser leg 13 causes those barbs 29 to tend to pull the medium 28 tautly across from one side of the frame to the other, while the edge 31 comes down into a clamping and holding engagement whereby the medium 28 is in effect not only compressed over the base 11 under the edge 31, but is tended to be pulled around and upwardly from that edge 31 in a tensioning manner. The edge 31 prevents undue local tearing out of the medium 28 by the pulling of the barbs 29, these barbs 29 being spaced especially close as to cause the medium 28 to be tensioned en masse.

A feature to be noted in respect to the fingers 25 and 26 is that they are required to be forced through the slot 22, and have sufficient spring in the metal to spring backwardly into the position indicated in Fig. 5 to prevent their withdrawal. In other words, the overall width of "the slot 22 is less than the height of the extreme ends of the fingers 25 and 26 from the side of the foot 23 which is in contact with the inside of the enclosing leg 12. The height of the foot 23 is less than the height of the leg 12, and likewise the height of the tongue 21 is less so that the members 21 and 23 which appear between the base 11 and the presser leg 13 may be engaged under that presser leg 13, particularly by reason of the radius 30 provided between the enclosing leg 12 and the presser leg 13, Fig. 6.

As shown in Fig. 4, upon the downward bending of the presser leg 13, the underside of the radius 30 contacts the upper marginal edge of the foot 23 to firmly seat the foot lower marginal edge against the base 11. The foot 23 is thereby compressively retained in a firmly seated manner between thme members 13 and 11 to further prevent any possibility of twisting of the members and 10A from the general planar interconnection.

Due to the various sizes and shapes of frames which are required in the industry, assembly operations may be performed by modifying the frame construction to that shown in Figs. 8-10. As shown in Fig. 8, three segments 35, 36, and 37 are integrally interconnected through bends forming right angle corners 38 and 39, thus providing a U-shaped member for the rectangular form of frame. To permit this bending, the lower base 11 is mitered as above described to abut along the lines 17. A fourth segment 40, being a single side segment, completes the frame construction by interengaging end portions 41 and 42 of the respective segments 35 and 37. In this form of the invention, a foot 43 identical to the previously described foot 23, is turned at a right angle from each end 44 and 45 of the segment 40 to be received through vertically extending slots 46 and 47 provided in the enclosing legs 48 and 49 of the respective segments 35 and 37. Staples 50 are then passed through the opposing ends of the base 11 to insure a rigid corner construction and further prevent displacement of one member from the other.

In some instances the size of the frame to be produced makes it impractical to integrally interconnect through bends any of the various segments employed in constructing the frame, and therefore, a plurality of single side frame segments are interconnected one with another to form the completed frame. Four of such segments 51, 51a, 51b and 510 are shown in Fig. 9 wherein each segment is identical one with the other, each having a foot 52 turned at a right angle from one end 53 while the other end portion 54 is provided with a foot re: ceiving slot 55 as above described. In this manner, the respective segments interengage one another to form a sturdy frame construction having'the slot of each segment receive therethrough the foot of the segment lying adjacent thereto. As above described, staples 56 are passed through abutting ends of the various interengaged frame segments as security means against displacement thereof.

As shown in Fig. 10, the frame may also be constructed in a very economical manner by having a plurality of frame segments 57, 58, 59, and 60 integrally interconnected through bends forming right angle corners 61, 62, and 63. A foot 64 is turned at a right angle from the free end 65 of the segment 60 to be received through a verti cally extending slot 66 provided adjacent the end of the enclosing leg 67 of the segment 57, thereby rigidly interconnecting the remaining frame corner to produce a com pleted construction. To permit this bending of the integral corners, the lower base 11 is again mitered as above described to abut along the lines 17, and staples 68 are passed through the opposing ends of the base 11 along this line of abutment as further rigidity and displacement prevention means.

It is therefore to be seen that we have provided a rather unique and simplified construction, and yet one which is extremely effective for the purposes intended, and while we have described the invention in the several particular forms, it is obvious that structural changes may be embodied without departing from the spirit of the invention, and we therefore desire not to be limited to those precise forms beyond the limitations which may be imposed by the following claim.

We claim:

A device for retaining a marginal edge portion of a loosely arranged filtering medium comprising a channel member open along one side and having a base leg; an enclosing leg disposed approximately at right angles to the base leg; and a presser leg integral with and bendable from along, and substantially longitudinally coextensive with said enclosing leg, and extending in spaced relation from and over said base leg; said presser leg having a continuous straight line outer free edge; and a plurality of integral, longitudinally spaced apart barbs extending approximately at ninety degrees from said presser leg and directed toward said base leg; each of said barbs being spaced from but adjacent said free edge and the points of the barbs terminating in aligned points; said filtering {71;} s I medium edge portion resting on and along said base leg; and upon bending said presser towa-rd the base leg, the points of said barbs initiallyengage the filter portion and draw the edge portion of the filter medium over the.

base leg toward said enclosing leg, followed by said presser leg edge compressibly ni-ging and clamping the filter me dium against the baseflg, said free edge bearing on a continuous line along the medium spaced from the line of barb points, the barbs tensioning the medium prior to the clamping of the medium against the base leg.

. 6 References Cited in the file of this patent UNITED STATES PATENTS Mautner Apr. 10, 1928 Bradley Oct. 27, 1942 Cartter et a1. June 10, 1947 Hambrecht et a1. July 17, 1956 Breckheimer Jan. 20, 1959 FOREIGN PATENTS Canada May 28. 1957 

